My Lexus RC has a coolant leak at the water pump. Is a $750 quote fair?

Short answer: An RC owner at 46,000 miles was quoted $750 for a water pump, and other owners called that reasonable for OEM parts and labor. Don't put it off for long. A leaking pump can suddenly leak a lot. If it's a rattle near the pump rather than a leak, it may be the thermostat, which is a cheaper part. The valley plate leak RC F owners talk about doesn't apply to the V6 cars.

Symptom: A shop finds a coolant leak at the water pump, or you hear a rattle from the thermostat area at the front of the engine.

What to check first

1. Check coolant level with the engine cold.
2. Look for dried pink crust or drips around the water pump.
3. If there's a rattle, have the thermostat checked.
4. Get a second quote if you want, but don't wait months.
5. Run your VIN at nhtsa.gov/recalls.

Likely causes

1. Water pump seal or gasket leaking. The water pump moves coolant through the engine. When its seal or gasket fails, coolant seeps out. One owner found their pump's rubber gasket had failed.
2. Thermostat broken. The thermostat is a spring-loaded valve that controls coolant flow. One owner's was broken and rattled.
3. Valley plate leak (RC F only). RC F owners know of a coolant leak under the intake (the valley plate), but owners say that doesn't apply to the V6 cars.

What it usually costs

One owner was quoted $750 for a water pump replacement, and others called that reasonable.

Is it safe to keep driving?

A slow seep you can watch for a short time while you book the repair. Stop driving if the temperature rises or you lose a lot of coolant.

DIY or shop?

A thermostat swap is DIY for many owners. Water pump replacement is doable for experienced DIYers but most use a shop.

Recalls, bulletins and complaints in plain words

• Recalls: NHTSA lists fuel pump recalls (18V107000, 20V012000, 20V682000) and a tire label recall (22V615000) for some RC years. None are about the cooling system, but the fuel pump recalls can cause stalling, so check your VIN. Check your VIN at nhtsa.gov/recalls. If your car is part of a recall, the dealer fixes it for free.
• Plain words: The complaint count below shows how often owners reported problems that mention these words to NHTSA. A count is not proof of a defect.
• NHTSA complaints: 5 keyword-matched complaints for Lexus RC 300 / RC 350 2015–2024 (of 34 unique complaints queried, NHTSA complaints API by model year, queried 2026-10-31; keywords: water pump, coolant, leak, rattle, noise) (NHTSA returned no data for 76 model-year queries). This counts complaints that mention these words. It is not a defect finding.

What owners report

• In Dealership found an engine coolant leak (RC 300, 46k miles) on Reddit r/LexusRC, an RC 300 owner at 46,000 miles was told during maintenance that there was a coolant leak and quoted $750 to replace the water pump. Most owners said to fix it soon, one called $750 reasonable for OEM parts and labor, and another said the pump's rubber gasket was what had failed on theirs. An RC F owner mentioned the valley plate leak, and others said that isn't a V6 issue.
• In Mechanic help on Reddit r/LexusRC, an owner of a 2017 RC 350 F Sport at about 110,000 miles heard a rattle from a part on the engine that looked like the water pump. Others identified it as the thermostat. The engine was warming up suspiciously fast, which made commenters think the thermostat was broken.

Quick tip

$750 for an OEM pump is a fair price. Get it done before the leak picks the worst possible day to get worse.

Vehicle focus: Lexus RC 300 and RC 350, 2015-2024.

Safety / mechanic note

An overheating engine can be damaged quickly. Verify with a mechanic.